Malate synthase from Gossypium hirsutum |
| |
Authors: | Jan A. Miernyk Richard N. Trelease |
| |
Affiliation: | Department of Botany and Microbiology, Arizona State University, Tempe, AZ 85281, U.S.A. |
| |
Abstract: | Malate synthase was purified 2000-fold from cotyledons of dark-germinated cotton, Gossypium hirsutum. The purified enzyme had a pH optimum of 8.2, and an absolute requirement for a divalent cation. Only glyoxylate and acetyl-CoA served as condensation partners. Results obtained with functional-group directed inhibitors suggest the presence of lysine, tyrosine and histidine residues in the active site. Temperature optimum was 40°, and energy of activation was 3.3 kcal/mol. The MW of cotton malate synthase, determined by rate-zonal density gradient sedimentation, was 750 000. Initial-rate studies indicated Michaelis-Menten kinetics. Inhibition by substrate analogs, plus substrate-interaction kinetics gave results consistent with a sequential bireactant mechanism. |
| |
Keywords: | Gossypium hirsutum Malvaceae cotton malate synthase glyoxylate cycle purification kinetic analyses reaction mechanism. |
本文献已被 ScienceDirect 等数据库收录! |
|